An out of office message is a compact text that conveys the most important facts: How long you’ll be unreachable, when your contacts can expect an answer, (optionally) the reason for the absence, and, if necessary, a personal note. A referral to another email address, e.g. to one of your colleagues, is often helpful or even necessary.
The one I’ve always wished I was brave enough to write was the one I once got which simply said:

This is true! The nuclear option also helps the recently returned vacationer understand what is a priority and what isn’t. But, as boyd wrote, “if you just turn off your email with no warning, you're bound to piss off your friends, family, colleagues, and clients.” The blog post offers some helpful steps to make a clean break feasible — they include communicating with colleagues about the sabbatical long in advance, managing expectations of those who rely on you, creating a backdoor for true emergencies, and then, right before going away, reminding everyone about the sabbatical once again.
Who says an autoresponder needs to be impersonal? You can use your OOO message to continue building a relationship with present and potential customers by showing off the knowledge and products you have to offer. You can include a case study, a downloadable to your latest report, or a link to an excellent blog post you published. Not only does this further your credibility, but it also allays the feelings of frustration customers might feel while not being able to reach you.